/*
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Rhino code, released
 * May 6, 1999.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1997-1999
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Roger Lawrence
 *   Mike McCabe
 *   Igor Bukanov
 *   Ethan Hugg
 *   Bob Jervis
 *   Terry Lucas
 *   Milen Nankov
 *   Pascal-Louis Perez
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License Version 2 or later (the "GPL"), in which
 * case the provisions of the GPL are applicable instead of those above. If
 * you wish to allow use of your version of this file only under the terms of
 * the GPL and not to allow others to use your version of this file under the
 * MPL, indicate your decision by deleting the provisions above and replacing
 * them with the notice and other provisions required by the GPL. If you do
 * not delete the provisions above, a recipient may use your version of this
 * file under either the MPL or the GPL.
 *
 * ***** END LICENSE BLOCK ***** */

package com.google.javascript.rhino;

import com.google.common.annotations.GwtIncompatible;
import com.google.javascript.rhino.jstype.TernaryValue;

/**
 * Helper methods for parsing JavaScript.
 * These methods use unsupported features in GWT's emulation of java.lang.Character.
 *
 * TODO(moz): Add a GWT-compatible version in the super-source directory.
 */
@GwtIncompatible("Unsupported java.lang.Character fields")
public class TokenUtil {
  static boolean isJSIdentifier(String s) {
    int length = s.length();

    if (length == 0
        || Character.isIdentifierIgnorable(s.charAt(0))
        || !Character.isJavaIdentifierStart(s.charAt(0))) {
      return false;
    }

    for (int i = 1; i < length; i++) {
      if (Character.isIdentifierIgnorable(s.charAt(i))
          || !Character.isJavaIdentifierPart(s.charAt(i))) {
        return false;
      }
    }
    return true;
  }

  /* As defined in ECMA.  jsscan.c uses C isspace() (which allows
   * \v, I think.)  note that code in getChar() implicitly accepts
   * '\r' == \u000D as well.
   */
  public static boolean isJSSpace(int c) {
    if (c <= 127) {
      return c == 0x20 || c == 0x9 || c == 0xC || c == 0xB;
    } else {
      return c == 0xA0
          || Character.getType((char) c) == Character.SPACE_SEPARATOR;
    }
  }

  public static boolean isJSFormatChar(int c) {
    return c > 127 && Character.getType(c) == Character.FORMAT;
  }

  public static boolean isWhitespace(int c) {
    return Character.isWhitespace(c);
  }

  /**
   * Copied from Rhino's ScriptRuntime
   */
  public static TernaryValue isStrWhiteSpaceChar(int c) {
    switch (c) {
      case '\u000B': // <VT>
        return TernaryValue.UNKNOWN;  // IE says "no", ECMAScript says "yes"
      case ' ': // <SP>
      case '\n': // <LF>
      case '\r': // <CR>
      case '\t': // <TAB>
      case '\u00A0': // <NBSP>
      case '\u000C': // <FF>
      case '\u2028': // <LS>
      case '\u2029': // <PS>
      case '\uFEFF': // <BOM>
        return TernaryValue.TRUE;
      default:
        return (Character.getType(c) == Character.SPACE_SEPARATOR)
            ? TernaryValue.TRUE : TernaryValue.FALSE;
    }
  }
}